Frequently Asked Questions
Does Delphi have an equivalent to the Visual Basic SendKeys function?
Question:
Does Delphi have an equivalent to the Visual Basic SendKeys
function?
Answer:
The following example demonstrates procedures that provide the
capibility of sending keystrokes to any window control capable of
receiving keyboard input. You may use this technique to toggle
the num lock, caps lock, and scroll lock keys under Windows NT.
This same technique works for toggling caps lock and scroll lock
keys under Windows 95, but it will not work for num lock.
Note that there are four procedures provided: SimulateKeyDown(),
SimulateKeyUp(), SimulateKeystroke(), and SendKeys(), to allow greater
control in your ability to send keystrokes.
The SimulateKeyDown(), SimulateKeyUp(), and SimulateKeystroke()
procedures expect a virtural key code (like VK_F1).
The SimulateKeystroke() procedure accepts an extra parameter that is
useful when simulating the PrintScreen key. When extra is set to zero,
the entire screen will be captured to the windows clipboard. When
extra is set to one, only the active window will be captured.
The four button click methods demonstrate the use of these functions:
ButtonClick1 - Toggles the cap lock.
ButtonClick2 - Captures the entire screen to the clipboard.
ButtonClick3 - Capture the active window to the clipboard.
ButtonClick4 - Set the focus to an edit control and sends it a string.
Example:
procedure SimulateKeyDown(Key : byte);
begin
keybd_event(Key, 0, 0, 0);
end;
procedure SimulateKeyUp(Key : byte);
begin
keybd_event(Key, 0, KEYEVENTF_KEYUP, 0);
end;
procedure SimulateKeystroke(Key : byte;
extra : DWORD);
begin
keybd_event(Key,
extra,
0,
0);
keybd_event(Key,
extra,
KEYEVENTF_KEYUP,
0);
end;
procedure SendKeys(s : string);
var
i : integer;
flag : bool;
w : word;
begin
{Get the state of the caps lock key}
flag := not GetKeyState(VK_CAPITAL) and 1 = 0;
{If the caps lock key is on then turn it off}
if flag then
SimulateKeystroke(VK_CAPITAL, 0);
for i := 1 to Length(s) do begin
w := VkKeyScan(s[i]);
{If there is not an error in the key translation}
if ((HiByte(w) <> $FF) and
(LoByte(w) <> $FF)) then begin
{If the key requires the shift key down - hold it down}
if HiByte(w) and 1 = 1 then
SimulateKeyDown(VK_SHIFT);
{Send the VK_KEY}
SimulateKeystroke(LoByte(w), 0);
{If the key required the shift key down - release it}
if HiByte(w) and 1 = 1 then
SimulateKeyUp(VK_SHIFT);
end;
end;
{if the caps lock key was on at start, turn it back on}
if flag then
SimulateKeystroke(VK_CAPITAL, 0);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
{Toggle the cap lock}
SimulateKeystroke(VK_CAPITAL, 0);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
{Capture the entire screen to the clipboard}
{by simulating pressing the PrintScreen key}
SimulateKeystroke(VK_SNAPSHOT, 0);
end;
procedure TForm1.Button3Click(Sender: TObject);
begin
{Capture the active window to the clipboard}
{by simulating pressing the PrintScreen key}
SimulateKeystroke(VK_SNAPSHOT, 1);
end;
procedure TForm1.Button4Click(Sender: TObject);
begin
{Set the focus to a window (edit control) and send it a string}
Application.ProcessMessages;
Edit1.SetFocus;
SendKeys('Delphi Is RAD!');
end;
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